Brass disc for air pump, 1761
1761
Brass disc with a small perforation plug in centre
1800-1899
Special objective, 20th century
1901-1970
Stage with seven window aperture disc
1801-1900
Objective disc with seven lenses
1841-1870
Flanged brass disc for air pump
Box of "Hydroflex" carborundum abrasive discs 7/16" type B
1930-1955
Objective disc with four objectives
1771-1800